No abstract

Although urban soils are strongly influenced by human activities, they provide a wide range of Ecosystem Services (ES) as long as they are not sealed off. This is a major sustainability issue as the loss of soil functions directly impacts ES and further on the possibility to adapt to the effects of the climate crisis. Green Infrastructure (GI) measures can be utilized to restore previously covered soil surfaces and compensate for lost soil functions. We conducted a systematic literature review to investigate the extent of peer-reviewed publications on GI measures in (peri-) urban areas covering soil-related ES. After identifying the relevant publications (n = 284), we generated an overview of the annual, spatial, and thematic distribution of the publications. Then, we employed an extended content analysis of the published focus topics to assess the representation of soil-related ES provided by GI. The content analysis revealed that the representation of soil-related ES in GI measures focused heavily on the contribution of soil to stormwater management. Detailed assessment of the interconnection of GI measures with key soil-related ES were missing. So far, the assessment of the loss of soil-related ES is not covered extensively in GI research publications.

Green Infrastructure measures such as seepage troughs are an integral part of sustainable urban rainwater management. In Austria, seepage troughs are currently almost exclusively produced with a 30 cm thick active soil filter passage made of topsoil. A standard seed mix is used as vegetation, which usually consists of only three different turfgrass species. During a three-year trial, engineered soils with improved properties (increased water storage capacity, infiltration rate and pore volume) were tested for their suitability as seepage troughs compared to topsoil. In addition to the standard turf seed mix, a flowering turf seed mix (34 species) and flowering meadow seed mix (53 species) were applied. The engineered and reference soils were analyzed for infiltration rate, vitality, cover ratio and inflorescence. The results were further assessed with the evaluation chart showing quantitatively the suitability of the tested soils for rainwater management. The investigations showed that engineered soils in combination with flowering meadow seed mix lead to the best results. Therefore, this type of vegetation for seepage troughs is recommended for future applications. The reference alternatives cannot be recommended.

In the context of establishing green infrastructure in cities, urban retrofit has presumably larger area potential than ground-based green. To support the large-scale advancement of urban green, the assessment of greenable potential plots in the building stock, both on horizontal and on vertical scale, provides first indispensable indications for decision-making. However, reliable and solid data to the state of the buildings is currently not available. The research study Urbane GmbA explored a new methodological approach, based on publicly available geo-data, and applied it at two study sites in high-density urban quarters in Vienna. The combination of a GIS-based analysis with digital and on-site photos allowed for the creation of a Level of Detail 2 (LOD2) 3D-model and subsequently the estimation of the green retrofit potential of roofs and facades. Comprehensive maps with the data of the 2D building footprints provide valuable information for planners, including building characteristics and greenable area potential. The approach proved to provide more comprehensive information including building characteristics fundamental to the planning and decision-making process. The achieved results are merged with an evaluation matrix generated for attributing available facade and roof greening systems. This allows for more focused decision support for the retrofit of the building stock towards more sustainable and resilient district development.

At conventional construction sites, the removal of soil and other excavated materials causes enormous mass movement, with a significant climate impact and contribution to global CO2 release. This study aimed to generate a Circular Soil concept for reusing excavated materials by creating engineered soils for landscape construction at large building sites. Engineered soils act as a substitute for natural soils and fulfill vital technical and soil functions when installing an urban green infrastructure (GI). In a field study, the vegetation performance on engineered soils was evaluated to establish a methodological approach, to assess the applicability of the Circular Soil concept. First, the technical specifications (grain-size distribution) were modeled for intensive green roof and turfgrass applications. Then, the soil components were optimized, mixed, installed and tested for greenery purposes, focusing on plant growth performance indicators (vitality, projective cover ratio and grass-herb ratio) to assess the vegetation performance. The results showed that the engineered soils match the performance of the reference soil alternatives. In conclusion, the Circular Soil concept has a high potential to contribute considerably to sustainable on-site soil management and the circular economy. It can be applied on a larger scale for urban GI development and sustainable resources management in the landscaping and construction sector.